﻿using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.IO;
using System.Threading;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;

public partial class common_download : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        //string filename = Request.Params["name"];
        //string url = Request.Params["url"];
        //Page.Response.Clear();
        //bool success = ResponseFile(Page.Request, Page.Response, filename, url, 1024000);
        //if (!success)
        //    Response.Write("下载文件出错！");
        //Page.Response.End();

        string url = FileHelper.Encrypt("c:/secret.jar");
        link.NavigateUrl = "~/common/download.aspx?fn=" + url;
    }

    public static bool ResponseFile(HttpRequest _Request, HttpResponse _Response, string _fileName, string _fullPath,
                                    long _speed)
    {
        try
        {
            FileStream myFile = new FileStream(_fullPath, FileMode.Open, FileAccess.Read, FileShare.ReadWrite);
            BinaryReader br = new BinaryReader(myFile);
            try
            {
                _Response.AddHeader("Accept-Ranges", "bytes");
                _Response.Buffer = false;
                long fileLength = myFile.Length;
                long startBytes = 0;

                double pack = 10240; //10K bytes
                //int sleep = 200;   //每秒5次   即5*10K bytes每秒
                int sleep = (int) Math.Floor(1000*pack/_speed) + 1;
                if (_Request.Headers["Range"] != null)
                {
                    _Response.StatusCode = 206;
                    string[] range = _Request.Headers["Range"].Split(new char[] {'=', '-'});
                    startBytes = Convert.ToInt64(range[1]);
                }
                _Response.AddHeader("Content-Length", (fileLength - startBytes).ToString());
                if (startBytes != 0)
                {
                    //Response.AddHeader("Content-Range", string.Format(" bytes {0}-{1}/{2}", startBytes, fileLength-1, fileLength));
                }
                _Response.AddHeader("Connection", "Keep-Alive");
                _Response.ContentType = "application/octet-stream";
                _Response.AddHeader("Content-Disposition",
                                    "attachment;filename=" + HttpUtility.UrlEncode(_fileName, System.Text.Encoding.UTF8));

                br.BaseStream.Seek(startBytes, SeekOrigin.Begin);
                int maxCount = (int) Math.Floor((fileLength - startBytes)/pack) + 1;

                for (int i = 0; i < maxCount; i++)
                {
                    if (_Response.IsClientConnected)
                    {
                        _Response.BinaryWrite(br.ReadBytes(int.Parse(pack.ToString())));
                        Thread.Sleep(sleep);
                    }
                    else
                    {
                        i = maxCount;
                    }
                }
            }
            catch
            {
                return false;
            }
            finally
            {
                br.Close();

                myFile.Close();
            }
        }
        catch
        {
            return false;
        }
        return true;
    }


    protected void Button1_Click(object sender, EventArgs e)
    {
        /*
         微软为Response对象提供了一个新的方法TransmitFile来解决使用Response.BinaryWrite
         下载超过400mb的文件时导致Aspnet_wp.exe进程回收而无法成功下载的问题。
         代码如下：
         */
        string strFileName = "c:/secret.jar";
        Response.ContentType = "application/x-zip-compressed";
        Response.ContentEncoding = System.Text.Encoding.GetEncoding("UTF-8");
        
        Response.AddHeader("Content-Disposition", "attachment;filename=" + Server.UrlPathEncode(strFileName));

        strFileName = Server.UrlPathEncode(strFileName);// 解决文件名的乱码问题.

        Response.TransmitFile(strFileName);
    }



    protected void Button2_Click(object sender, EventArgs e)
    {
        /*
         using System.IO;
         
         */

        string fileName = "目标文件名.rar";//客户端保存的文件名
        string filePath = "c:/secret.jar";//Server.MapPath("DownLoad/aaa.txt");//路径
        filePath = Server.UrlPathEncode(filePath);
        FileInfo fileInfo = new FileInfo(filePath);
        Response.ContentEncoding = System.Text.Encoding.GetEncoding("UTF-8");
        Response.Clear();
        Response.ClearContent();
        Response.ClearHeaders();
        Response.AddHeader("Content-Disposition", "attachment;filename=" + fileName);
        Response.AddHeader("Content-Length", fileInfo.Length.ToString());
        Response.AddHeader("Content-Transfer-Encoding", "binary");
        Response.ContentType = "application/octet-stream";
        Response.ContentEncoding = System.Text.Encoding.GetEncoding("gb2312");
        Response.WriteFile(fileInfo.FullName);
        Response.Flush();
        Response.End();

    }
    protected void Button3_Click(object sender, EventArgs e)
    {
        string fileName = "aaa.txt";//客户端保存的文件名
        string filePath = Server.MapPath("DownLoad/aaa.txt");//路径

        System.IO.FileInfo fileInfo = new System.IO.FileInfo(filePath);

        if (fileInfo.Exists == true)
        {
            const long ChunkSize = 102400;//100K 每次读取文件，只读取100Ｋ，这样可以缓解服务器的压力
            byte[] buffer = new byte[ChunkSize];

            Response.Clear();
            System.IO.FileStream iStream = System.IO.File.OpenRead(filePath);
            long dataLengthToRead = iStream.Length;//获取下载的文件总大小
            Response.ContentType = "application/octet-stream";
            Response.AddHeader("Content-Disposition", "attachment; filename=" + HttpUtility.UrlEncode(fileName));
            while (dataLengthToRead > 0 && Response.IsClientConnected)
            {
                int lengthRead = iStream.Read(buffer, 0, Convert.ToInt32(ChunkSize));//读取的大小
                Response.OutputStream.Write(buffer, 0, lengthRead);
                Response.Flush();
                dataLengthToRead = dataLengthToRead - lengthRead;
            }
            Response.Close();
        }
    }


    protected void Button4_Click(object sender, EventArgs e)
    {
        string fileName = "aaa.txt";//客户端保存的文件名
        string filePath = Server.MapPath("DownLoad/aaa.txt");//路径

        //以字符流的形式下载文件
        FileStream fs = new FileStream(filePath, FileMode.Open);
        byte[] bytes = new byte[(int)fs.Length];
        fs.Read(bytes, 0, bytes.Length);
        fs.Close();
        Response.ContentType = "application/octet-stream";
        //通知浏览器下载文件而不是打开
        Response.AddHeader("Content-Disposition", "attachment;  filename=" + HttpUtility.UrlEncode(fileName, System.Text.Encoding.UTF8));
        Response.BinaryWrite(bytes);
        Response.Flush();
        Response.End();
    }
}
